The present invention generally relates to a storage-and-forward apparatus, and more particularly to a storage-and-forward apparatus by which various services for a communication terminal coupled to a private line located in-plant can be improved.
Recently, a storage-and-forward apparatus which controls a plurality of communication terminals such as facsimiles to produce various services for users of the communication terminal has been proposed.
For example, the storage-and-forward apparatus accommodates a plurality of public lines and a plurality of private lines which are located in an in-plant, and switches connections of the public lines and the private lines. The storage-and-forward apparatus can operate in a direct transmission mode and a substitute receiving mode. For example, when a facsimile coupled to a private line transmits a command requesting a communication in the direct transmission mode to the storage-and-forward apparatus, the storage-and-forward apparatus calls a destination identified by the facsimile via a public line, and connects the private line for the facsimile to the public line for the destination. Then the storage-and-forward apparatus directly relays image information transmitted from the facsimile to the destination. A request for the communication in the direct transmission mode is often made in a case where it is necessary for the facsimile to rapidly transmit the image information to the destination.
The storage-and-forward apparatus has an image memory which is used in the substitute receiving mode. For example, when a facsimile coupled to a private line transmits a command requesting the communication process in the substitute receiving mode to the storage-and-forward apparatus, the storage-and-forward apparatus stores image information transmitted via the private line from the facsimile in the image memory. And then, when a predetermined waiting time elapses, the storage-and-forward apparatus connects the private line, on which a call out is produced, to the public line to which the destination is coupled. Then the image information is read out from the image memory and is transmitted via the public line to the destination.
A request for the substitute receive mode described above is generally made in a case where it is unnecessary for the facsimile to rapidly transmit the image information to the destination.
When the facsimile transmits a command requesting the communication process in the direct transmission mode to the storage-and-forward apparatus, the storage-and-forward apparatus calls the public line coupled to the destination, as described above. In this case, if the destination is communicating with another facsimile, the storage-and-forward apparatus cannot connect the private line to the public line to which the destination is coupled. That is, the communication between the calling facsimile and the destination in direct transmission mode fails. As a result, the user of the facsimile must operate the facsimile so that it transmits a command requesting the communication process in either the direct transmission mode or the substitute receiving mode to the storage-and-forward apparatus again.
That is, if the destination is communicating with another communication terminal when the calling facsimile transmits a command for requesting the communication process in the direct transmission mode, the number of operations, in the calling facsimile, for transmitting the image information increases.